In order to reduce the shock of a frontal crash of an automobile, shock-absorbing members are attached to an automotive front bumper. Shock-absorbing members absorb the energy due to a crash. A hollow box body (so-called crash box) is deformed by the shock of a crash and thereby absorbs the energy.
Today, various shock-absorbing members are in practical use, an example of which is disclosed in Patent Literature 1.
The shock-absorbing member disclosed in Patent Literature 1 is “a shock-absorbing member including: a first portion that is a tubular body having an outer wall made of a metal sheet; a second portion that is a bent portion formed to be continuous with the outer wall of the first portion and to be bent outwardly; and a third portion that is continuous with the second portion and forms a support portion for the second portion, wherein bending deformation continuously occurs in which a length of a folded-back portion formed by folding back of the outer wall of the first portion caused by a shock power applied from the end of the first portion in the axial direction of the tubular body increases so that a shock energy is absorbed, and wherein the first portion has a plurality of ridge lines that extend in the axial direction of at least a part of the outer wall of the tubular body where the bending deformation continuously occurs” (see claim 1 of Patent Literature 1).
“The first portion and the third portion are both extend in a direction substantially parallel to the axial direction of the tubular body” (see claim 10 of Patent Literature 1).